Across
1
Line touching circle at one point
6
Rectangle with four equal sides
7
Collection of distinct elements
8
Sum divided by count
10
Mathematical rule or equation
13
Repeated addition
Down
2
Number less than zero
3
Three-sided polygon
4
Longest side of a right triangle
5
Part of a line with two endpoints
9
Reference line in a graph
11
Line crossing from corner to corner
12
Math using letters for unknown values